Some computer systems include an integrated display-and-input panel, such as a touch screen. This feature may be found in systems ranging from small, handheld devices to large-format, multi-user platforms. Various technologies may be combined to furnish suitable display and input functionality in the panel. For example, liquid-crystal display (LCD) technology may be combined with resistive, capacitive, or infrared (IR) vision-based input technology.
Irrespective of the technologies used, it is desirable for a display-and-input panel to exhibit high energy efficiency with respect to illumination. This consideration is relevant for handheld devices, where energy use limits battery life, and for large-format platforms, which consume significant power for illumination. Besides extending battery life and limiting energy usage, increased illumination efficiency may in some cases reduce the production cost of a display-and-input panel by reducing the number of light-emissive elements needed to provide a suitable level of illumination. These factors may be especially relevant when the input technology in the panel is vision-based, using an additional illumination source separate from that of the display.